diff --git a/gtk2_ardour/port_group.cc b/gtk2_ardour/port_group.cc
index f96d465564..aabe07157b 100644
--- a/gtk2_ardour/port_group.cc
+++ b/gtk2_ardour/port_group.cc
@@ -209,7 +209,8 @@ PortGroup::io_from_bundle (boost::shared_ptr<ARDOUR::Bundle> b) const
 		return boost::shared_ptr<IO> ();
 	}
 
-	return (*i)->io;
+	boost::shared_ptr<IO> io ((*i)->io.lock ());
+	return io;
 }
 
 /** Remove bundles whose channels are already represented by other, larger bundles */
@@ -306,6 +307,7 @@ struct RouteIOs {
 	}
 	
 	boost::shared_ptr<Route> route;
+	/* it's ok to use a shared_ptr here as RouteIOs structs are only used during ::gather () */
 	std::list<boost::shared_ptr<IO> > ios;
 };
 
diff --git a/gtk2_ardour/port_group.h b/gtk2_ardour/port_group.h
index 3ae1df697d..f0bb1c4c58 100644
--- a/gtk2_ardour/port_group.h
+++ b/gtk2_ardour/port_group.h
@@ -75,7 +75,7 @@ public:
 	    boost::shared_ptr<ARDOUR::Bundle> bundle;
 	    /** IO whose ports are in the bundle, or 0.  This is so that we can do things like adding
 		ports to the IO from matrix editor menus. */
-	    boost::shared_ptr<ARDOUR::IO> io; 
+	    boost::weak_ptr<ARDOUR::IO> io; 
 	    Gdk::Color colour;
 	    bool has_colour;
 	    PBD::ScopedConnection changed_connection;